Through-tubing perforating systems



July- 28, 1959 Filed Aug. 2. 1955 3 Sheets- Sheet 1 INVENTOR.

July 28, 1959 w. R. CANNADAY I I THROUGH-TUBING PERFORATING SYSTEMS 3 Sheets-Sheet 2 Filed Aug. 2, 1955 44/44/1 41 2. cam/wavy INVENTOR.

July 28, 1959 w. R. CANNADAY 2,896,721 THROUGH-TUBING PERFORATING SYSTEMS 3 Sheets-Sheet 3 Filed Aug. 2, 1955 (IIIIIIIA lll'l z E K k 0 6 a I Z W 2 s 1- x 5 w $Y\\\\\\\\\\\\ \H q x INVENTOR.

rraen/a/ r' 2,896,721 Patented July 1959 THROUGH-TUBING PERFORATING SYSTEMS William R. Cannaday, Houston, Tex., assignor, by mesne assignments, to Dresser Industries, Inc., Dallas, Tex., a corporation of Delaware Application August 2, 1955, Serial No. 525,893

4 Claims. (Cl. 166-555) This invention relates to equipment for the production of oil or gas from a cased well, and particularly to an improvement in the means and method for perforating the casing in a well at extreme depths or under conditions of high fluid or gaseous pressure.

It is general practice to utilize tubing within cased wells to act as a conduit for the delivery of oil or gas. Such inner tubing may be substantially smaller in diameter than the casing. After tubing has been set, if it was desired to carry out operations such as gun perforating either before or after the well had been put on production, it has been necessary until recently to withdraw the tubing from the well. Servicing or reworking a well has in consequence been a costly and time-consuming operation.

Recently a new method has been widely adopted, known as the permanent well completion system. Once the tubing has been installed, it is substantially permanent. Servicing the well thereafter below the lower end of the tubing must be accomplished by tools, the largest dimension of which, perpendicular to the longitudinal axis of the well, is sufficiently less than the internal diameter of the tubing so that the tools may pass freely throughthe tubing. This dimension is known as the ring diameter of the tools.

Perforating guns to operate through tubing must, therefore, have ring diameters less than those which may be employed with the larger diameter casings. The cablesj used for running in are likewise generally of-smaller,

concentric, is subject to damage in running in through It is,

the packing glands used to seal :off high pressures. extremely difficulty to retain high pressures in the bore with such multistrand cable, since even though the suc-- water and mud tends to leak through the interstices. Ifthe particular tool to be employed is'a perforating gun,l the problem is additionally complicated by the inclusion in the stranded cable of one or more insulatedelectrical conductors.

The high pressure in ofiers a force resisting insertion equal to the cross-sectional area of the cable times the unit pressure within the bore: it is almost impossible to insert even a A cable against a resisting force in excess of 200 to 300 lbs. with-i out cumbersome and expensive pulling-in equipment.

Under such conditions the resistanceto the cable entry.

the bore also makes it very diffi-- cult to feed the cable into position. Borehole pressure;

ning in through tubing of a perforating gun supported by a single strand piano wireline. The gun can be located in a simple manner at a desired depth below the open lower end of the tubing. Firing may be accomplished with safety at any subsequent time by lowering a battery-- powered go-devil on a second run. The nonexpendable gun parts may then be retrieved on a third run by lowering the same tool as that utilized in the running operation, or any other conventional pulling tool. Each of these tools may be suspended on a single strand wireline, as

j in the first operation, to facilitate the retention of borehole pressure.

With the foregoing considerations in view, it is the general purpose and object of this invention to provide novel means for, and a method of, running a gun perfo rator on a solid wireline through tubing, fixing the perforator in a well below the open end of the tubing, firing the gun electrically by a self-powered unit, and retrieving the gun in a simple and expeditious manner.

A more particular object of the invention is to provide 1 a novel means and method of running a gun perforator through tubing on a single wireline, air 1d setting the gun in position with suspension tools locked in the tubing above the gun.

Another object of the invention is to provide an im-.

1 proved mandrel or supporting element for a gun perforator adapted to be run in the well through tubing on a wireline, beneath which element a gun perforator may be suspended at a desired depth below the lower open end of the tubing on a second wireline.

A further object of the invention is to provide a novel gun arrangement which may be fired electrically from a self-powered mechanism while the gun is suspended in a desired position below the lower open end of the tubing from a gun head seated in the tubing.

These and other objects and advantages of the present 1 invention will be apparent from a detailed consideration of the specification when read with the accompanying drawings, in which:

Figure 1 is an elevational view, partially broken away showing the general assembly of apparatus of the inventionin connection with a well;

7 Figure 2 is an elevational view, partially in section, of a lubricator showing initial stages of the insertion of a gun, the supporting mandrel, and its supporting equip-" ment in a well;

Figure 3 is a fragmentary-longitudinal sectional view showing details of connections between the supporting mandrel and tools for running in and retrieving the gun;

Figure 4 is a longitudinal sectional view showing the v I gun in position in a well for firing; cess1ve layers are rightly applied, high pressure 011, gas,

, sertion of the gun, and a quick coupling arrangement for removing the stufiing box;

Figure 7 is an elevational sectional view of the appa-, ratus of Figure 6 showing another one of the stages in the insertion of the gun.

.In the drawing the numeral 10 indicates a conventional well casing disposed in an earth borehole. To the top of this casing, above the surface 11 of the earth, is secured a casing head 12. The casing head may have one or, more branch pipes, such as that shown at 13, each supplied with a control valve 14. A string of tubing 15. extends downwardly through casing 10. The upper sec-.

These difficulties and disadvantages are-largely overcome by the present invention, envisages the run:

tion of the tubing is connected to a top flange 17 of the casing head 12 and communicates with a master valve, 20 secured thereon. The branch pipe 13' extends latera ly from he c si ead .1 and c mmun c gs with;

. 3 theannular space therein about the tubing 15 within casing 10. A nipple 21, a T 22, and a nipple 23 are connected in sequence to, and extend upwardly from, valve 20. A delivery pipe '24 is connected through a suitable valve 24A to the T 22. Through pipe 24 oil or gas from the well tubing is delivered to surface equipment, while other borehole fluid from the annulus between the tubing and well casing may be withdrawn through the branch pipe 13. A wireline seal valve or blowrout preventer 25 :is positioned on the upper end of nipple 23, and above blowout-.preventer 25 is connected a lubricator 26 surmounted by .a wireli-ne stufiing box 27. A conventional yoke structure may be suitably mounted on lubricator 26 to provide support for a sheave anranged to carry the wire suspension lines 30 and 46 seen in Figures 1 and 2. The yoke and sheave are well known elements in the art, and are "hence omitted from the drawing. A landing nipple 31 is suitably joined .to the lowermost section of tubing 15. Nipple 31 extends downwardly to any desired location above the well bot.- tom 32, and has an open lower end 33, as seen in Fig ure4.

Landing nipple 3.1 has an inwardly extending annular supporting shoulder .34 adapted to receive a removable gun-supporting mandrel or contact head 35. Mandrel 3.5 has an elongated body the upper portion of which is adapte to extend centrally downward through the annular supporting shoulder 34, and an enlarged intermediate portion 36. The enlarged portion 36 is shaped to define an annular shoulder 37 adapted to seat, as before them tioned on the supporting shoulder 34 of the landing nipp 3.1.

adapter .38 is sec red to the upp r end of mandrel 35 by a threaded connection 39 as seen in'Figurc 5. A. la 40 s similarly secured at the pper end of adap 3.8, and has n u de cut annula shoulder 41 .for eng gement i a un ng-in or retrieving tool.

Adapter 38 is bored to receive a bare-pointed contact member 42 which has an insulating coating 42A over the lower portion thereof. Suitable insulation .43 is provided between the remainder of contact member 42 and the adapter 38. Mandrel 35. has formed therein a bore 44 through which extends an electrical conductor 45. Conductor 45 is connected at its upper end to the lower end of pointed contact member 42, and at its lower end is connected electrically to electrical firing means within the gun 47, as indicated schematically in Figure 5. A suspension wire 46, which may conveniently be a single strand piano wireline, is secured to and extends downwardly from the lower end of mandrel 35 to support the perforating gun 47, which may have a plurality of explosive perforator devices disposed therein of either the bullet or the shaped charge type, for example. These perforator devices are arranged to be fired by an electrically ignited detonator or cap, not shown in detail. The firing is accomplished by a current supply means or source, hereinafter more fully described, and which is generally referred to as go-devil. Alternatively, as shown in Figures 2, 4 and 7, the contact point .42 may be electrically connected to the firing means within the gun 47 through either a conductor-containing or an insulatedconductor suspension cable 46 and the separate conductor 45 eliminated. In this embodiment, the electrical return is obtained through the borehole fluid, tubing 31 and the go-devil body 54.

Since the depth of supporting shoulder on seat 34 is known, the position of gun 47 for firing may be accurately predetermined by using a proper length of suspension wire or line 46. An alternative embodiment for locating gun 47 accurately involves the use of aselective nipple and cooperating mandrel arrangement. Another well known expedient which may be utilized is the slip type suspension, which may be anchored at any desired depth.

'Wireline sealing valve 25 and stufiing box 27 may be of generally-conventional construction. Such a valve will ssa'zz seal about a single element wireline, such as a piano wire and a separate conductor line when used, against much higher pressures than around a cable having a plurality of strands. Valve 25 has a pair of gate valve elements 47A mounted on transverse pivots 48 adapted to be externally controlled, and a pair of sealing elements 49 which engage closely around the wirelinerdo, and the conductor 45 if employed, when the valve is shut, as seen in Figure 2. Stufiing box 27 is of the full opening type, and incorporates one or more resilient split sealing rings 50 which are compressed to proper sealing condition by conventional pressure adjusting means such as a split packing bushing 51 and .a split compression vnut 52 having a threaded connection 52A witht'he stufiing box body and secured together by means. such as bolts, not shown.

A running-in tool 53 for the mandrel is shown in Figures 2 and 3. Tool 53 has a hollow body 54 secured to ,a piano wire suspension line 30. A plunger 55 is slidable "in body -54 but held against movement therein by a-shear pin 56. A core member 57 extends downwardly from plunger 55, with an annular tapered shoulder 58 increasing in diameter toward the lower end of the tool. The core member has an internal bore 59. A plurality of latching dogs 60 extends downwardly from body 54, and are formed with inward facing shoulders 61, the internal diameters of which increase toward the lower end of the tool. Theseshoulders are adapted to engage the tapered annular shoulder 58 of the core member when theplunger '55 is permitted to move axially by shearing of pin 56. Latching fingers 62 formed at the lower ends of dogs 60 extend inwardly and are, adapted to engage the-undercut annular shoulder 41 of mandrel collar 40. When shoulders 61 on the dogs engage shoulder 58 on the core, the dogs 60 are spread so that the fingers 62 are released from shoulder 41. The running-in tool 53 or an equivalent retrieving tool may be used to pull the mandrel and gun-out of the hole after firing.

In Figure 5 is shown a self-powered go-devil 63 secured to a piano wireline 30a. The go-devil is formed with a hollow body 64 containing a battery 65 having one or more dry cell-s. An adapter 66 may be secured to the lower endof the body 64 "by means such as a threaded connection 67. Within adapter 66 is a bore 68 having coaxially disposed therein an insulated conducting element having an upper portion 69 of relatively small diameter and a lower end portion 71 of relatively large diameter. The bore 68 is correspondingly enlarged at 68A to receive the enlarged lower end portion 71 of the conducting element, the whole being surrounded by insulation as shown at 70'. A contact nut 72 is threadably secured to the upper end of conducting element 69 to engage with the, centerterminal of battery 65, the opposite terminal of which is grounded to the battery case or go-devijl 'body. The battery case or go-devil body may be grounded in the usual manner as by contact springs 79. A bore 73 is coaxially formed in the lower end of the enlarged portion 71 of contact element, which bore is adapted to receive the bare upper pointed portion of a contact member'42 which extends coaxially upwardly from the upper end portion of mandrel 35. The bore 73 is sealed against entry of well bore fluids. by an arrangement including a collar 74 threadably secured in position to retain a diaphragm 77 across the lower end'of adapter 66, and to maintain an electrical and fluid seal for the lower end of 71 of con ducting element 69 at all times by retaining a pressureresisting insulating oil or grease filler 78 in bore 68A.

In using the invention the sequence of steps depends upon the distance below the bottom 33 of the landing nipple 31 at which the gun 47 is to be fired. If the firing were to occur only a short distance below, the length of the suspension wire 46 joining the gun to the mandrel 35 might be so short that the running in tools, the mandrel and the'gun could all be inserted in the lubricator at one time. In this event the "wireline scaling valve 25 would be closed, the stutfing box 27 opened to permit the insertion of these components, and then sealed around the suspending wireline 30, all as shown in the Figure 2. The blow-out preventer or wireline seal valve 25 could then be opened, and the entire string dropped into the hole until the mandrel came to rest on the supporting shoulder 34. The running in tool 53 would then be released from the mandrel by the use of jarring tools, not shown, and withdrawn into the lubricator. The wireline seal valve would next be closed and the stufiing box 27 opened to permit the running in tools to be entirely removed. The subsequent steps would follow the same pattern; that is, a go-devil would be inserted, the gun fired, and the go-devil and the nonexpendable parts of the gun thereafter removed from the hole by successive utilizations of the pressure lock constituted by the blow-out preventer 25 and the stuifing box 27, together with the master valve 20.

However, in the usual case, the gun will be fired some distance below the landing nipple bottom 33, so that the length of the gun, the suspending piano wire 46 and the mandrel 35 will be greater than the length of the lubricator 35. 'Where the well pressure is sufficiently high to require the use of sinker bars, the over-all tool length will present a still greater problem.

-Hence, when'the gun is dropped into the lower part of the lubricator, as shown at the lower part of Figure 2, the suspension or piano wire 46 will still extend out of the top and the mandrel will be some distance above the stufling box 27. Accordingly, the initial step after closing the stufling box is to open the blow-out preventer as in Figure 6 and lower the gun therethrough until it assumes the position shown in dot and dash outline in Figure 2. Lowering is continued until the mandrel reaches the position shown in Figure 7, that is, almost touching the top of the stufling box 27, and the blowout preventer or wireline seal valve 25 is then closed. Next, the stufling box 27 is reopened to permit the mandrel and running in tools to enter the lubricator. The tools are then further lowered to the position shown in the upper part of Figure 2 which allows stuffing box 27 to be closed and wireline sealing valve 25 to be reopened. The mandrel and running in tools then are lowered into the borehole, still occupying the relation to each other shown in Figure 3, and the lowering continued until the mandrel comes to rest on the landing nipple seat 34. The running in tool 53 must then be jarred loose by shearing the pin 56, which permits the latching fingers 62 to disengage from the undercut collar flange 41, after which the running in tool may be withdrawn, leaving the mandrel and gun in the position as shown in Figure 4. The sequence of steps for passing the running in tool back out through the blow-out preventer 25 and the stufiing box 27 while retaining the borehole pressure will be just the reverse of those used during entry.

At the desired time, the go-devil or an equivalent firing implement will be inserted and lowered through the well tubing, following a similar technique for going into the borehole against pressure. The conventionally springcentered go-devil will be suspended, preferably, on a piano wireline 30a and lowered until it engages the mandrel as shown in Figure 5. The go-devil is lowered until its diaphragm 77 is pierced by the contact point 42, and the latter passes through the insulating oil or grease 78 and engages within the contact bore 73.

The relative proportions of the go-devil and the tubing are so chosen that the resilient springs 79 will maintain the go-devil substantially centered during its lowering. These springs also serve as ground connection means between the go-devil container and the tubing as before mentioned. If, however, there is some axial misalignment between the contact point 42 and the end bore 73 of the go-devil, it will be corrected by the collar 74. The inner face 74A of the collar 74 is tapered 6 so as to guide the contact point 42 toward thecenter of the go-devil. Similarly, the entrance to the end bore 73 of the contact member is chamfered to assist the contact point 42 in entering easily. As soon as contact point 42 enters the bore 73, the circuit will be completed from the go-devil batteries to the ignition device in the gun, and the latter will fire. A number of possible return paths are available for current from the go-devil battery, cooperating with the one path provided either through the conductor 45 or the suspension piano wire 46.

The mandrel and the unexpended parts of the gun may be recovered by a subsequent use of the running in tool, or any other conventional retrieving implement which will hook over the undercut flange 41. The assembly may be withdrawn through the system described above for retaining the borehole pressure. Speed in using the system may be increased by using a conventional quick acting release for the stufling box, as shown in Figures 6 and 7.

From the foregoing description it will be seen that there has been provided a working tool for the treatment of cased wells which can be utilized when extremely high pressures are encountered, and in which the difficulty of sealing around conventional cables is eliminated. The use of a piano wire suspension cable, with or without an additional conducting wire makes it possible to seal satisfactorily against even the highest pressures encountered, and to fire the gun at safe times for both operators and equipment.

The foregoing is illustrative only, and the invention is not to be limited thereby, but includes various modifications within the skill of the art without departing from the scope of the invention as defined in the appended claims.

What is claimed is:

1. In a well having tubing therein terminating in a lower open end spaced above the well bottom, apparatus for perforating the well below the lower end of said tubing, comprising the combination of: supporting means disposed in said tubing adjacent said lower open end; a retrievable mandrel adapted to be lowered through said tubing to seat on said supporting means; lowering means for lowering and seating said mandrel on said supporting means, said lowering means including means for detaching said lowering means from said mandrel when said mandrel is seated on said supporting means; a gun arranged to be fired by electrical firing means in said gun; an elongated flexible member interconnecting said rnandrel and said gun, and arranged to suspend said gun from said mandrel at a position a substantial distance below said lower end of said tubing when said mandrel is seated on said supporting means; an electrical contact disposed at the upper end of said mandrel in electrical communication with the electrical firing means in said gun; and a go-devil containing an electrical current supply means adapted to be lowered through said tubing above said mandrel, after said first mentioned lowering means is removed from said tubing, and having an electrical contact electrically connected to said current supply means and engageable with the said electrical contact on said mandrel, to supply current to said electrical firing means to fire said gun.

2. In a well having tubing therein terminating in a lower open end spaced above the well bottom, apparatus for perforating the well below the lower end of said tubing, comprising the combination of: supporting means disposed in said tubing adjacent said lower open end; a retrievable mandrel adapted to be lowered through said tubing to seat on said supporting means; lowering means for lowering said mandrel through said tubing and seating said mandrel on said supporting means, said lowering means comprising a wireline carrying at its lower end means releasably attachable to said mandrel and releasable from said mandrel when said mandrel is seated On supporting means; a gun arranged to befired by velecttical fir ing means in said gun; an elongated flexible member interconnecting said mandrel and said gun, and arranged to suspend said gun from said mandrel at a position a substantial distance below said lower end of said tubing when said mandrel is seated on said supporting means; an electrical contact disposed at the upper end of said mandrel in electrical communication with the electrical firing means in said gun; and a ,go-devil containing an electrical current supply means adapted to be lowered through said tubing above said mandrel, after said first mentioned wireline is removed from said tubing, and having an electrical contact electrically connected to said current supply means and engageable with the said electrical contact on said mandrel, to supply current to said electrical firing means to fire said gun.

3. In a well having tubing set therein with thelower open end of said tubing located above the bottom of the well, the method of perforating the well below such tubing without removal of such tubing from the Well, comprising: lowering on a wireline through said tubing a supporting head from which is suspended a substantial distance therebelow a perforating gun, and anchoring said supporting head at a point adjacent the lower end of said tubing such that the said gun suspended from said supporting head is located entirely within the portion of the well below the lower end of said tubing; detaching said wireline from said supporting head and leaving said gun su p e n d we l a a r aid e ppvip said w re i e f s i ubi g; n xt lowering electr out u supply means suspended on a wireline said tub: ing into electrical contact with electrical contat means carried by said supporting head to. liresaid gun; next removing said electrical current supply means and its suspending wireline from said tubing and then lowering're' References Cited in the fileof patent UNITED STATES PAIENIS 2,476,137 Doll ,-v- ,J;u1 1-2, 1949 2,566,682 SWQetman Sept. 4,195.1 2,621,732 Ab r :De '16, 1952 2,631,671 r no a 1,7, 953 v2,638,981 ann May- .19, v -525 2,689,008 Allen Sept, 14, 1-254 2,690, K a y a vSppt- 8 .195 2,721 immon 9st .250. 9 

